1. Field
The following description relates to an apparatus and method for memory overlay in a multitasking system.
2. Description of the Related Art
As a function of a processor quickly develops and complexity of an application program also rapidly increases, a multitasking technology is being applied to process several tasks in one processor simultaneously, and thus, increases a use rate of the processor.
Generally, a computer system uses a hierarchical memory array structure.
In the memory array structure, a memory disposed close to a central processing unit (CPU) is fast, but has a relatively small capacity and is expensive. Conversely, a memory disposed far from the CPU is slow, but has a relatively large capacity and is inexpensive.
Thus, although an internal memory is superior to an external memory in terms of data processing, it may increase a cost of the system when the system includes several internal memories.
Accordingly, when a small-sized internal memory is efficiently shared in various tasks, a high performance of the system may be achieved.
Recently, in an embedded system, a high-speed internal memory called a scratch pad memory is being used, at a greater rate, for data processing.
An overlay scheme, instead of a virtual memory scheme, is widely used in the embedded system for sharing of the high-speed internal memory.
However, the virtual memory scheme induces a high cost for necessary paging hardware and is difficult to apply in a real-time computing system.